Device for adjusting height of vehicle

ABSTRACT

A vehicle height adjustment system includes: a cylinder housing part having an inner space configured to receive working fluid; a piston part positioned in the cylinder housing part, the piston part configured to move linearly, in response to a working fluid, in a moving direction along the cylinder housing part; and a rotation suppressing bracket coupled to the cylinder housing part and connected to a side surface of the piston part, the rotation suppressing bracket configured to suppress rotational movement with respect to the moving direction of the piston part.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority from and the benefit of Korean PatentApplication No. 10-2019-0106301 filed on Aug. 29, 2019, which is herebyincorporated by reference for all purposes as if set forth herein.

BACKGROUND Field

Exemplary embodiments relate to a vehicle height adjustment system, andmore particularly, a vehicle height adjustment system that is capable ofpreventing or reducing rotation of a piston part.

Discussion of the Background

A suspension system conventionally includes a suspension spring and ashock absorber to improve the quality of driving experience by absorbingvarious types of vibrations or impacts transferred from a road surface.

In the conventional suspension system, the suspension spring may includea leaf spring, a coil suspension spring, an air suspension, or the like.Among them, the air suspension may have an advantage that the height ofthe vehicle may be constantly maintained or adjusted. On the other hand,the air suspension additionally requires a device for adjusting anamount of air depending on conditions, such as a load, a device forcompressing air, and the like. Therefore, the use of air suspension isgenerally restricted to large vehicles such as a bus or a luxurypassenger vehicle.

A conventional vehicle height adjustment system may have a problem ofincreased number of parts and thus increased manufacturing cost. Also, apiston part conventionally used in a suspension system does not includea separate device for preventing or reducing its rotation. Suchunnecessary rotation caused by applying the vehicle height adjustmentsystem may degrade the overall durability of the damper rod.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the invention and,therefore, it may contain information that does not constitute priorart.

SUMMARY

Exemplary embodiments of the present invention provide a vehicle heightadjustment system capable of preventing or reducing the rotation of apiston part and thereby improving the durability of parts. The vehicleheight adjustment system according to the exemplary embodiments of thepresent invention may also reduce the number of parts and reduce themanufacturing cost.

Additional features of the invention will be set forth in thedescription which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention.

According to one or more exemplary embodiments, a vehicle heightadjustment system includes: a cylinder housing part having an innerspace configured to receive working fluid; a piston part positioned inthe cylinder housing part, the piston part configured to move linearly,in response to a working fluid, in a moving direction along the cylinderhousing part; and a rotation suppressing bracket coupled to the cylinderhousing part and connected to a side surface of the piston part, therotation suppressing bracket configured to suppress rotational movementwith respect to the moving direction of the piston part.

The piston part may include: a piston body positioned in the cylinderhousing part and configured to move linearly in the moving direction;and a side engagement groove part formed on a side surface of the pistonbody having a groove shape extending along the moving direction of thepiston body.

The rotation suppressing bracket may include a protrusion formed on theside surface of the piston part, the protrusion inserted into the sideengagement groove part.

The rotation suppressing bracket may include: a bracket body having ashape of a ring which is brought into contact with an end of thecylinder housing part; and a first engagement protrusion extending fromthe bracket body and inserted into the side engagement groove part.

The first engagement protrusion may include a plurality of firstengagement protrusion parts extending from the bracket body.

The cylinder housing part may include a fastening groove part formed onthe end of the cylinder housing part, and wherein the rotationsuppressing bracket may further include: a second engagement protrusionextending from the bracket body, and inserted into and engaged in thefastening groove part.

The second engagement protrusion may include a plurality of secondengagement protrusion parts extending from the bracket body.

The vehicle height adjustment system may further include: an outputcover fastened to the cylinder housing part while surrounding therotation suppressing bracket.

The vehicle height adjustment system may further include a damper rodpositioned in the piston part, the damper rod including a protrusionpart protruding from the damper rod, and the piston part may furtherinclude a guide part formed to have a groove shape facing the protrusionpart, and the protrusion part may be inserted into the guide part.

The protrusion part inserted into the guide part may be configured tosuppress rotational movement of the damper rod with respect to themoving direction.

According to one or more exemplary embodiments, a vehicle heightadjustment system includes: an output unit connected to a vehicle bodyfor reducing vibration, the output unit configured to change its lengthin response to transfer of working fluid to adjust a height of thevehicle body with respect to ground; a connection pipe connected to theoutput unit; and an input unit connected to the connection pipe, theinput unit configured to supply the working fluid to the output unitthrough the connection pipe, wherein the output unit includes: acylinder housing part having an inner space configured to receive theworking fluid; a piston part positioned in the cylinder housing part,the piston part configured to move linearly in a moving direction inresponse to the working fluid transferred to the cylinder housing part,the piston part including: a groove shape formed on a side surfacethereof, extending along the moving direction thereof; and a rotationsuppressing bracket coupled to the cylinder housing part, the rotationsuppressing bracket including a protrusion formed on the side surface ofthe piston part, the protrusion inserted into the groove shape.

The output unit may include at least one of: a front wheel output unitconfigured to adjust a height of a front wheel-side vehicle body; and arear wheel output unit configured to adjust a height of a rearwheel-side vehicle body.

The input unit may include: an input piston housing part containing theworking fluid; and an input piston part configured to move in a verticaldirection to transfer the working fluid between the input unit and theoutput unit.

The input unit may further include: a driving part configured togenerate rotational power for driving the input piston; and a reductionpart connected between the driving part and the input piston, thereduction part configured to generate a torque by increasing therotational power of the driving part and transmit the torque to theinput piston part.

The input unit may further include: a lead nut part configured toreceive the torque from the reduction part and rotate in response to thereceived torque; and a lead screw rotatably coupled to the lead nut partand connected to the input piston part, the lead screw may be configuredto move in the vertical direction in response to the rotation of thelead nut part to move the input piston part in the vertical direction.

The vehicle height adjustment system may further include a replenishmentunit connected to the input unit, the replenishment unit configured tosupply the working fluid into the input unit.

The vehicle height adjustment system may further include a supply pipeconnected between the input unit and the replenishment unit, and thereplenishment unit may be configured to supply the working fluid intothe input unit through the supply pipe in response to a negativepressure formed in the input unit due to a leakage of the working fluidfrom operation.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention, andtogether with the description serve to explain the principles of theinvention.

FIG. 1 is a perspective view illustrating a vehicle height adjustmentsystem in accordance with an exemplary embodiment of the disclosure.

FIG. 2 is a front view of the vehicle height adjustment system inaccordance with the exemplary embodiment of the disclosure.

FIG. 3 is a cross-sectional view illustrating a process of the vehicleheight adjustment system in accordance with the exemplary embodiment ofthe disclosure in a low mode.

FIG. 4 is a cross-sectional view illustrating a process of the vehicleheight adjustment system in accordance with the exemplary embodiment ofthe disclosure in a high mode.

FIG. 5 is a view illustrating a process of increasing the length of anoutput unit in accordance with the exemplary embodiment of thedisclosure to increase the height of a vehicle body.

FIG. 6 is a view illustrating a process of reducing the length of theoutput unit in accordance with the exemplary embodiment of thedisclosure to reduce the height of the vehicle body.

FIG. 7 is a perspective view illustrating a front wheel output unit inaccordance with the exemplary embodiment of the disclosure.

FIG. 8 is an exploded perspective view of the front wheel output unit inaccordance with the exemplary embodiment of the disclosure.

FIG. 9 is a cross-sectional view illustrating a process of raising adamper rod part in accordance with the exemplary embodiment of thedisclosure.

FIG. 10 is a cross-sectional view illustrating a process of lowering thedamper rod part in accordance with the exemplary embodiment of thedisclosure.

FIG. 11 is a perspective view illustrating a rotation suppressingbracket in accordance with the exemplary embodiment of the disclosure.

FIG. 12 is a cross-sectional view illustrating a process of locking afastening nut to a nut coupling part of the damper rod part inaccordance with the exemplary embodiment of the disclosure.

FIG. 13 is a plan view illustrating a process of inserting a firstengagement protrusion of the rotation suppressing bracket into a sideengagement groove part in accordance with the exemplary embodiment ofthe disclosure.

FIG. 14 is a perspective view illustrating a process of disassembling anoutput cover from a cylinder housing part in accordance with theexemplary embodiment of the disclosure.

FIG. 15 is a perspective view illustrating an input unit in accordancewith the exemplary embodiment of the disclosure.

FIG. 16 is an exploded perspective view of the input unit in accordancewith the exemplary embodiment of the disclosure.

FIG. 17 is a perspective view illustrating a lead nut part assembled inan input housing part in accordance with the exemplary embodiment of thedisclosure.

FIG. 18 is a perspective view illustrating a state in which an inputpiston part is disassembled from the input housing part in accordancewith the exemplary embodiment of the disclosure.

FIG. 19 is a cross-sectional view illustrating a process of lowering theinput piston part in accordance with the exemplary embodiment of thedisclosure.

FIG. 20 is a cross-sectional view illustrating a process of raising theinput piston part in accordance with the exemplary embodiment of thedisclosure.

FIG. 21 is a cross-sectional view illustrating a replenishment unitconnected to the input unit in accordance with the exemplary embodimentof the disclosure.

FIG. 22 is a cross-sectional view illustrating a process of transferringworking fluid stored in the replenishment unit to the input unit inaccordance with the exemplary embodiment of the disclosure.

FIG. 23 is a perspective view illustrating a valve part in accordancewith the exemplary embodiment of the disclosure.

FIG. 24 is a cross-sectional view illustrating a different type of valvepart in accordance with the exemplary embodiment of the disclosure.

FIG. 25 is a perspective view illustrating a state in which a lead screwand the input piston part are connected by a third locking member inaccordance with the exemplary embodiment of the disclosure.

FIG. 26 is a cross-sectional view illustrating the input piston part andthe lead screw separated from each other with a hydraulic seal memberinterposed therebetween, in accordance with the exemplary embodiment ofthe disclosure.

FIG. 27 is a cross-sectional view illustrating the input piston part andthe lead screw coupled with each other with the hydraulic seal memberinterposed therebetween, in accordance with the exemplary embodiment ofthe disclosure.

FIG. 28 is a cross-sectional view illustrating a state in which the leadscrew and the input piston part are connected with each other by thethird locking member in accordance with the exemplary embodiment of thedisclosure.

FIG. 29 is a perspective view illustrating a state in which the leadscrew and the input piston part are connected with each other by a firstlocking member in accordance with the exemplary embodiment of thedisclosure.

FIG. 30 is a cross-sectional view illustrating the input piston part andthe lead screw temporarily assembled, in accordance with the exemplaryembodiment of the disclosure.

FIG. 31 is a cross-sectional view illustrating the lead screw and theinput piston part connected with each other by the first locking memberin accordance with the exemplary embodiment of the disclosure.

FIG. 32 is a perspective view illustrating the lead screw and the inputpiston part connected with each other by a second locking member inaccordance with the exemplary embodiment of the disclosure.

FIG. 33 is a cross-sectional view illustrating the input piston part andthe lead screw temporarily assembled, in accordance with the exemplaryembodiment of the disclosure.

FIG. 34 is a cross-sectional view illustrating the lead screw and theinput piston part connected with each other by the second locking memberin accordance with the exemplary embodiment of the disclosure.

FIG. 35 is an exploded perspective view of a rear wheel output unit inaccordance with the exemplary embodiment of the disclosure.

FIG. 36 is a front view of the rear wheel output unit in accordance withthe exemplary embodiment of the disclosure.

FIG. 37 is a front view illustrating the rotation of a vehicle pistonpart being prevented or reduced, in accordance with the exemplaryembodiment of the disclosure.

FIG. 38 is a plan view illustrating a rotation suppressing part inaccordance with the exemplary embodiment of the disclosure.

FIG. 39 is a cross-sectional view illustrating the length of the rearwheel output unit increased in accordance with the exemplary embodimentof the disclosure.

FIG. 40 is a cross-sectional view illustrating the length of the rearwheel output unit reduced in accordance with the exemplary embodiment ofthe disclosure.

FIG. 41 is a view illustrating a stiffness adjustment unit connected toa connection pipe, in accordance with the exemplary embodiment of thedisclosure.

FIG. 42 is a cross-sectional view illustrating a first stopper beingbrought into contact with a fixed stopper in accordance with theexemplary embodiment of the disclosure.

FIG. 43 is a cross-sectional view illustrating the fixed stopperpositioned between the first stopper and a second stopper in accordancewith the exemplary embodiment of the disclosure.

FIG. 44 is a cross-sectional view illustrating the second stopper beingbrought into contact with the fixed stopper in accordance with theexemplary embodiment of the disclosure.

FIG. 45 is a diagram schematically illustrating the front wheel outputunit in accordance with the exemplary embodiment of the disclosure.

FIG. 46 is a diagram schematically illustrating the vehicle heightadjustment system operating in the high mode and the low mode, inaccordance with the exemplary embodiment of the disclosure.

FIG. 47 is a diagram schematically illustrating the front wheel outputunit connected to the vehicle body with a load of the connected vehiclebody applied to the front wheel output unit, in accordance with theexemplary embodiment of the disclosure.

FIG. 48 is a diagram illustrating a first load transferred to the frontwheel output unit when the vehicle height adjustment system is operatedin the high mode in accordance with the exemplary embodiment of thedisclosure.

FIG. 49 is a diagram illustrating a second load transferred to the frontwheel output unit when the vehicle height adjustment system is operatedin the low mode in accordance with the exemplary embodiment of thedisclosure.

FIG. 50 is a diagram illustrating a first table stored in a control unitin accordance with the exemplary embodiment of the disclosure.

FIG. 51 is a diagram illustrating a second table stored in the controlunit in accordance with the exemplary embodiment of the disclosure.

FIG. 52 is a block diagram of the vehicle height adjustment system inaccordance with the exemplary embodiment of the disclosure.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

The invention is described more fully hereinafter with reference to theaccompanying drawings, in which embodiments of the invention are shown.This invention may, however, be embodied in many different forms andshould not be construed as limited to the embodiments set forth herein.Rather, these embodiments are provided so that this disclosure isthorough, and will fully convey the scope of the invention to thoseskilled in the art. Like reference numerals in the drawings denote likeelements.

Various advantages and features of the present invention and methodsaccomplishing thereof will become apparent from the followingdescription of embodiments with reference to the accompanying drawings.However, the present invention is not be limited to the embodiments setforth herein but may be implemented in many different forms. The presentembodiments may be provided so that the disclosure of the presentinvention will be complete, and will fully convey the scope of theinvention to those skilled in the art and therefore the presentinvention will be defined within the scope of claims. Like referencenumerals throughout the description denote like elements.

Unless defined otherwise, it is to be understood that all the terms(including technical and scientific terms) used in the specification hasthe same meaning as those that are understood by those who skilled inthe art. Further, the terms defined by the dictionary generally usedshould not be ideally or excessively formally defined unless clearlydefined specifically. It will be understood that for purposes of thisdisclosure, “at least one of X, Y, and Z” can be construed as X only, Yonly, Z only, or any combination of two or more items X, Y, and Z (e.g.,XYZ, XYY, YZ, ZZ). Unless particularly described to the contrary, theterm “comprise”, “configure”, “have”, or the like, which are describedherein, will be understood to imply the inclusion of the statedcomponents, and therefore should be construed as including othercomponents, and not the exclusion of any other elements.

Various exemplary embodiments are described herein with reference tosectional illustrations that are schematic illustrations of idealizedexemplary embodiments and/or intermediate structures. As such,variations from the shapes of the illustrations as a result, forexample, of manufacturing techniques and/or tolerances, are to beexpected. Thus, exemplary embodiments disclosed herein should not beconstrued as limited to the particular illustrated shapes of regions,but are to include deviations in shapes that result from, for instance,manufacturing. Thus, the regions illustrated in the drawings areschematic in nature and their shapes are not intended to illustrate theactual shape of a region of a device and are not intended to belimiting.

FIG. 1 is a perspective view illustrating a vehicle height adjustmentsystem in accordance with an exemplary embodiment of the disclosure,FIG. 2 is a front view of the vehicle height adjustment system inaccordance with the exemplary embodiment of the disclosure, FIG. 3 is across-sectional view illustrating a process of the vehicle heightadjustment system in accordance with the exemplary embodiment of thedisclosure in a low mode, FIG. 4 is a cross-sectional view illustratinga process of the vehicle height adjustment system in accordance with theexemplary embodiment of the disclosure in a high mode, FIG. 5 is a viewillustrating a process of increasing the length of an output unit 10 inaccordance with the exemplary embodiment of the disclosure to increasethe height of a vehicle body, FIG. 6 is a view illustrating a process ofreducing the length of the output unit 10 in accordance with theexemplary embodiment of the disclosure to reduce the height of thevehicle body, and FIG. 52 is a block diagram of the vehicle heightadjustment system in accordance with the exemplary embodiment of thedisclosure.

As illustrated in FIGS. 1, 2, 3, 4, 5, and 6 and 52, a device 1 foradjusting a height of a vehicle in accordance with an exemplaryembodiment of the disclosure includes an output unit 10, an input unit100, a replenishment unit 130, a stiffness adjustment unit 200, ahydraulic pressure measurement unit 140, a control unit 150, adisplacement sensor 160, a rotation measurement sensor 170, and avehicle height sensor 180.

The output unit 10 may have various shapes without departing from atechnical idea that the output unit 10 is connected to a vehicle body 6to reduce vibration and the length of the output unit 10 is changed dueto transfer of working fluid 4 to adjust the height of the vehicle body6 with respect to the ground. The output unit 10 in accordance with theexemplary embodiment includes at least any one of a front wheel outputunit 20 which adjusts the height of a front wheel-side vehicle body 6and a rear wheel output unit 60 which adjusts the height of a rearwheel-side vehicle body 6.

The output unit 10 and the input unit 100 are connected through aconnection pipe 5, and, by the operation of the input unit 100, theworking fluid 4 flows from the input unit 100 to the output unit 10 orfrom the output unit 10 to the input unit 100. The output unit 10includes the front wheel output unit 20 which is installed on the frontwheel of the vehicle body 6 and the rear wheel output unit 60 which isinstalled on the rear wheel of the vehicle body 6 (refer to FIG. 35).

The input unit 100 linearly moves an input piston part 113 by using therotational power of a driving part 101 to control the flow of theworking fluid 4 from the output unit 10 to the input unit 100, or fromthe working fluid 4 to the output unit 10.

As illustrated in FIGS. 4 and 5, as a piston part 27 is moved upward bythe working fluid 4 introduced into an inner space 45 of the front wheeloutput unit 20, the height of the vehicle body 6 is increased by adamper rod part 22 which is moved upward together with the piston part27. A lower portion of the front wheel output unit 20 is connected to awheel support 8 which rotatably supports a wheel 7, and an upper portionof the front wheel output unit 20 supports the vehicle body 6.

As illustrated in FIGS. 3 and 6, as the working fluid 4 flows from thefront wheel output unit 20 toward the input unit 100, the piston part 27is moved downward. Therefore, the height of the vehicle body 6 isreduced by the damper rod part 22 which is moved downward together withthe piston part 27.

FIG. 7 is a perspective view illustrating the front wheel output unit inaccordance with the exemplary embodiment of the disclosure, FIG. 8 is anexploded perspective view of the front wheel output unit in accordancewith the exemplary embodiment of the disclosure, FIG. 9 is across-sectional view illustrating a process of raising the damper rodpart in accordance with the exemplary embodiment of the disclosure, FIG.10 is a cross-sectional view illustrating a process of lowering thedamper rod part in accordance with the exemplary embodiment of thedisclosure, FIG. 11 is a perspective view illustrating the rotationsuppressing bracket 50 in accordance with the exemplary embodiment ofthe disclosure, FIG. 12 is a cross-sectional view illustrating a processof locking a fastening nut 34 to a nut coupling part 24 of the damperrod part 22 in accordance with the exemplary embodiment of thedisclosure, FIG. 13 is a plan view illustrating a process of inserting afirst engagement protrusion 52 of the rotation suppressing bracket 50into a side engagement groove part 30 in accordance with the exemplaryembodiment of the disclosure, and FIG. 14 is a perspective viewillustrating a process of disassembling an output cover 49 from acylinder housing part 40 in accordance with the exemplary embodiment ofthe disclosure.

As illustrated in FIGS. 1 and 7, 8, 9, 10, 11, 12, 13, and 14, the frontwheel output unit 20 may have various shapes without departing from atechnical idea that the front wheel output unit 20 is installed on thefront wheel of the vehicle body 6, is connected with the input unit 100,is supplied with the working fluid 4 and thereby is changed in itslength. The front wheel output unit 20 in accordance with the exemplaryembodiment includes a first elastic part 21, the damper rod part 22, aprotrusion part 25, the piston part 27, a guide part 32, a fastening nut34, a cylinder housing part 40, a stopper 47, a dust cover 48, an outputcover 49, and a rotation suppressing bracket 50.

The damper rod part 22 which extends in a vertical direction along thelengthwise direction of the front wheel output unit 20 is connected to adamper for damping vibration. The first elastic part 21 which dampsvibration by using a spring is installed around the damper rod part 22.The lower end of the first elastic part 21 is supported by a seat memberwhich is fastened to the outer surface of the damper rod part 22.

The damper rod part 22 may have various shapes without departing from atechnical idea that the lower portion of the damper rod part 22 ispositioned in the piston part 27 and the upper portion of the damper rodpart 22 extends upward out of the piston part 27. The damper rod part 22in accordance with the exemplary embodiment includes a damper rod body23 which extends into a piston body 28 and is connected to theprotrusion part 25, and a nut coupling part 24 which forms a thread onthe outer surface of the damper rod body 23. The damper rod body 23 hasa circular rod shape, and the nut coupling part 24 is positionedadjacent to the lower end of the damper rod body 23.

The protrusion part 25 may have various shapes without departing from atechnical idea that the protrusion part 25 forms the shape of aprojection protruding outward from the damper rod part 22. Theprotrusion part 25 in accordance with the exemplary embodiment is formedintegrally with the damper rod part 22, or is fastened to the damper rodpart 22 by being fabricated as a separate member. The protrusion part 25is inserted into the guide part 32 to be prevented or reduced from beingrotated.

The protrusion part 25 in accordance with the exemplary embodimentprojects on both sides of the damper rod body 23, and is inserted intothe guide part 32 which is formed in the piston part 27, to be preventedor reduced from being rotated.

The piston part 27 may have various shapes without departing from atechnical idea that the piston part 27 is positioned in the cylinderhousing part 40, is linearly moved by the working fluid 4 and is formedwith grooves on the outer surface thereof in a moving direction thereof.The piston part 27 in accordance with the exemplary embodiment includesthe piston body 28, a side engagement part 29, and a side engagementgroove part 30.

The piston body 28 has a cylindrical shape which surrounds the outersurface of the damper rod part 22, and extends in the verticaldirection. The piston body 28 is positioned in the cylinder housing part40, and is installed to be linearly movable along the cylinder housingpart 40.

The side engagement part 29 projects outward from the piston body 28,and is installed at a position that faces the end of a first body part42 of the cylinder housing part 40. Since the side engagement part 29which projects outward from the piston body 28 in a ring shape forms aplurality of projections, a plurality of seals and backup rings areinstalled on the side engagement part 29. The side engagement part 29forms band-shaped projections along the outer surface of the piston body28, and is installed in a horizontal direction.

When observed at the position of the side engagement part 29, the lowerportion of the piston body 28 is formed to have an outer diametersmaller than an outer diameter of the upper portion of the piston body28. The guide part 32 is formed on the inner surface of the upperportion of the piston body 28 such that the protrusion part 25 isinserted into and engaged in the guide part 32.

The upper portion of the piston body 28 includes the side engagementgroove part 30 on the side surface of the piston body 28 along themoving direction of the piston body 28. The side engagement groove part30 forms the grooves which extend in the vertical direction.

The guide part 32 may have various shapes without departing from atechnical idea that the protrusion part 25 is inserted into the guidepart 32 formed in the piston part 27 facing the protrusion part 25. Theguide part 32 in accordance with the exemplary embodiment may have arecessed shape inside the piston body 28 facing the protrusion part 25.

The protrusion part 25 and the guide part 32 may be applied to varioussuspension types, and may prevent or reduce unnecessary rotation uponinstallation of the device 1 for adjusting a height of a vehicle.Therefore, the durability of the parts of the front wheel output unit 20may be improved. The technology of preventing or reducing the rotationof the damper rod part 22 by using the protrusion part 25 and the guidepart 32 may be applied to a front wheel multi-link or double wishbonetype.

The damper rod part 22 has a thread shape as the nut coupling part 24adjacent to the lower end thereof, and has the protrusion part 25 at themiddle portion thereof. The protrusion part 25 may be directly formed onthe damper rod part 22, or may be formed separately from the damper rodpart 22 and be assembled to the damper rod part 22 through a method suchas welding.

The protrusion part 25 is inserted into the guide part 32 to beprevented or reduced from being rotated, and, as a method for couplingthe protrusion part 25 and the piston part 27, various methods such askey coupling and spline coupling may be used. The nut coupling part 24which is formed adjacent to the lower end of the damper rod part 22projects out of the lower end of the piston part 27 and is then coupledwith the fastening nut 34. Since the upper surface of the fastening nut34 is brought into contact with the lower end of the piston part 27, thedamper rod part 22 and the piston part 27 are moved together upward anddownward. The fastening nut 34 is locked to the nut coupling part 24,and supports the piston body 28.

In the operation of the device 1 for adjusting a height of a vehicle,since the rotation of the damper rod part 22 is prevented or reduced andthe upward and downward movement thereof is permitted, the durability ofparts brought into contact with the damper rod part 22 may be improved.Further, since the unnecessary behavior of the vehicle body 6 isprevented, vehicle stability may be improved.

The cylinder housing part 40 may have various shapes without departingfrom a technical idea that the cylinder housing part 40 has an innerspace which is supplied with the working fluid 4. The cylinder housingpart 40 in accordance with the exemplary embodiment includes the firstbody part 42 and a second body part 44.

The first body part 42 may have various shapes without departing from atechnical idea that first body part 42 is positioned outside or surroundthe piston part 27 and has a working space that guides the upward anddownward movement of the piston part 27. The first body part 42 inaccordance with the exemplary embodiment has a cylindrical shape whichis extends in the vertical direction, and the snap ring-shaped stopper47 is coupled to the lower end of the first body part 42. Since the snapring is installed at the lower end to face the fastening nut 34, whenthe fastening nut 34 is moved downward together with the damper rod part22, the fastening nut 34 is engaged with the stopper 47 and the stopper47 stops the fastening nut 34 from being released downward.

The second body part 44 extends upward from the first body part 42 whileforming a step portion with the first body part 42, and have a shapecorresponding to the side surface of the piston part 27. The outerdiameters of the first body part 42 and the second body part 44 are thesame, but the inner diameter of the first body part 42 is smaller thanthe inner diameter of the second body part 44. Thus, the upper end ofthe first body part 42 which is connected with the second body part 44forms a step portion, and forms the inner space 45 which is suppliedwith the working fluid 4. The inner space 45 which is supplied with theworking fluid 4 is formed between the side engagement part 29 and theend of the first body part 42 and between the second body part 44 andthe piston body 28.

Since the working fluid 4 supplied into the inner space 45 pushes upwardthe side engagement part 29, the damper rod part 22 is moved upwardtogether with the piston part 27. The distance between the inner surfaceof the first body part 42 and the inner surface of the second body part44 corresponds to a height by which the side engagement part 29 projectsoutward from the piston body 28.

The dust cover 48 covers the upper end of the piston part 27, andprevents or reduces foreign substances from being introduced into thepiston part 27. The dust cover 48 is fastened to the upper end of thepiston part 27 and is moved upward and downward together with the pistonpart 27. The dust cover 48 is installed to have a shape which covers theopen upper end of the piston part 27.

The rotation suppressing bracket 50 may have various shapes withoutdeparting from a technical idea that the rotation suppressing bracket 50is coupled to the cylinder housing part 40 and is connected to the sidesurface of the piston part 27 to prevent or reduce the rotation of thepiston part 27. The rotation suppressing bracket 50 in accordance withthe exemplary embodiment has a projection inserted into the sideengagement groove part 30 formed on the side surface of the piston part27, and includes a bracket body 51, a first engagement protrusion 52 anda second engagement protrusion 53.

As the projection of the rotation suppressing bracket 50 is insertedinto the side engagement groove part 30 which is formed in the pistonpart 27, the rotation of the piston part 27 may be prevented or reduced.Alternatively, a projection may be formed on the piston part 27 and agroove part may be formed in the rotation suppressing bracket 50 facingthe piston part 27, to prevent or reduce the rotation of the piston part27.

The piston part 27 and the rotation suppressing bracket 50 are preventedor reduced from being rotated by a connection structure of groove andprojection shapes. A groove or a projection for preventing or reducingthe rotation of the piston part 27 may be formed in not the rotationsuppressing bracket 50 but other parts which face the piston part 27.

The bracket body 51 has the shape of a ring which is brought intocontact with the end of the cylinder housing part 40, and is stacked onthe upper end of the cylinder housing part 40.

The first engagement protrusion 52 may have various shapes withoutdeparting from a technical idea that the first engagement protrusion 52extends from the bracket body 51 and is inserted into the sideengagement groove part 30. The first engagement protrusion 52 inaccordance with the exemplary embodiment is provided in a plural numberin the bracket body 51, and extends in the horizontal direction. Thefirst engagement protrusion 52 projects inward of the bracket body 51and is inserted into the side engagement groove part 30 which is formedin the piston part 27, thereby preventing or reducing the rotation ofthe piston part 27.

The second engagement protrusion 53 may have various shapes withoutdeparting from a technical idea that the second engagement protrusion 53extends from the bracket body 51 and is inserted into and engaged in afastening groove part 46 which is formed on the end of the cylinderhousing part 40. The second engagement protrusion 53 in accordance withthe exemplary embodiment is provided in a plural number in the bracketbody 51, extends downward and is inserted into the fastening groove part46, thereby preventing or reducing the rotation of the bracket body 51.

The rotation of the piston part 27 is prevented or reduced by therotation suppressing bracket 50, and the rotation of the damper rod part22 is prevented or reduced as the protrusion part 25 is inserted intothe guide part 32 which is formed inside the piston part 27. Therefore,regardless of a suspension type, unnecessary rotation may be preventedor reduced when the device 1 for adjusting a height of a vehicle isapplied.

Thus, a separate additional device such as a sensor may be easilyinstalled, and the durability of the parts of the front wheel outputunit 20 may be improved.

The output cover 49 for fastening the rotation suppressing bracket 50 isfastened to the cylinder housing part 40 while surrounding the rotationsuppressing bracket 50. The output cover 49 is locked to the upper endof the cylinder housing part 40 while surrounding the rotationsuppressing bracket 50.

FIG. 35 is an exploded perspective view of the rear wheel output unit 60in accordance with the exemplary embodiment of the disclosure, FIG. 36is a front view of the rear wheel output unit 60 in accordance with theexemplary embodiment of the disclosure, FIG. 37 is a front viewillustrating the rotation of a vehicle piston part 62 being prevented orreduced, in accordance with the exemplary embodiment of the disclosure,FIG. 38 is a plan view illustrating a rotation suppressing or reducingpart in accordance with the exemplary embodiment of the disclosure, FIG.39 is a cross-sectional view illustrating the length of the rear wheeloutput unit 60 increased in accordance with the exemplary embodiment ofthe disclosure, and FIG. 40 is a cross-sectional view illustrating thelength of the rear wheel output unit 60 reduced in accordance with theexemplary embodiment of the disclosure.

As illustrated in FIGS. 35, 36, 37, 38, 39, and 40, the rear wheeloutput unit 60 may have various shapes without departing from atechnical idea that the rear wheel output unit 60 is connected to thevehicle body 6 to reduce vibration and the length of the rear wheeloutput unit 60 is changed due to transfer of the working fluid 4 toadjust the height of the vehicle body 6. The rear wheel output unit 60in accordance with the exemplary embodiment includes a vehicle pistonpart 62, a vehicle cylinder part 66, a rotation suppressing part 70, arotation suppressing guide part 75, a rear wheel elastic support part80, a piston guide 90, and a rear wheel stopper 92.

The rear wheel output unit 60 may be applied to not only the rear wheelof the vehicle body 6 but also a multi-link or a MacPherson strut.

The vehicle piston part 62 may have various shapes without departingfrom a technical idea that the vehicle piston part 62 is provided on therear wheel of a vehicle, is positioned in the vehicle cylinder part 66and is linearly moved by the working fluid 4. The vehicle piston part 62in accordance with the exemplary embodiment has a T shape, and is movedupward and downward in the vehicle cylinder part 66.

The vehicle piston part 62 includes a rear wheel piston body 63 which ispositioned in the vehicle cylinder part 66 and is provided to belinearly movable along the vehicle cylinder part 66, and an outerengagement part 64 which projects outward from the rear wheel pistonbody 63 and faces the end of a second cylinder body 68.

The rear wheel piston body 63 has the shape of a rod which extends inthe vertical direction, and has a projection for assembling an airtightseal, on an outer surface thereof. The outer engagement part 64 has theshape of a plate which extends in the horizontal direction on the upperend of the rear wheel piston body 63, and is positioned over the vehiclecylinder part 66.

The rotation suppressing part 70 is inserted into the rotationsuppressing guide part 75 formed on a side surface of the vehicle pistonpart 62 facing the rotation suppressing part 70. The rotationsuppressing guide part 75 may have a groove shape which extends in thevertical direction.

The vehicle cylinder part 66 has an inner space which is supplied withthe working fluid 4, and is formed with a passage which guides theupward and downward movement of the rear wheel piston body 63, in thevertical direction. The vehicle cylinder part 66 in accordance with theexemplary embodiment includes a first cylinder body 67, the secondcylinder body 68, and a body support member 69.

The first cylinder body 67 is positioned outside or surrounding thevehicle piston part 62, and guides the upward and downward movement ofthe vehicle piston part 62. The second cylinder body 68 extends from thefirst cylinder body 67 while forming a step portion with the firstcylinder body 67, and may have a shape which faces the side surface ofthe vehicle piston part 62.

The second cylinder body 68 extends upward from the first cylinder body67, and a space into which the working fluid 4 is supplied is defined inthe second cylinder body 68.

The body support member 69 extends in the horizontal direction at theupper end of the second cylinder body 68, and is coupled with therotation suppressing part 70. The outer engagement part 64 is positionedon the body support member 69. When the vehicle piston part 62 islowered, as the outer engagement part 64 is brought into contact withthe body support member 69, the further downward movement of the vehiclepiston part 62 is prevented or reduced.

An inner space which is supplied with the working fluid 4 is definedbetween the projection which projects outward from the side surface ofthe rear wheel piston body 63 and the end of the first cylinder body 67.Also, an inner space 45 which is supplied with the working fluid 4 isdefined between the rear wheel piston body 63 and the second cylinderbody 68. Since a process in which the vehicle piston part 62 is movedupward and downward by the supply of the working fluid 4 is similar tothe operation of the front wheel output unit 20, detailed descriptionthereof will be omitted herein.

The rotation suppressing part 70 may have various shapes withoutdeparting from a technical idea that the rotation suppressing part 70 isfastened to the vehicle cylinder part 66 and has a projection whichprojects toward the vehicle piston part 62. The rotation suppressingpart 70 in accordance with the exemplary embodiment includes a rotationsuppressing body 71, a rotation suppressing projection 72, and a bodylocking member 73.

The rotation suppressing body 71 is fastened to the body support member69 of the vehicle cylinder part 66. The rotation suppressing projection72 extends from the rotation suppressing body 71, is inserted into therotation suppressing guide part 75, and prevents or reduces the rotationof the vehicle piston part 62.

The body locking member 73 has a bolt shape, passes through the rotationsuppressing body 71 with the rotation suppressing body 71 brought intocontact with the upper surface of the body support member 69, and isthen locked to the body support member 69.

The rotation suppressing part 70 prevents or reduces the unnecessaryrotation of the vehicle piston part 62 when the device 1 for adjusting aheight of a vehicle is operated, regardless of a suspension type.Therefore, a task for assembling a separate additional device such as asensor on the rear wheel output unit 60 may be easily performed.Moreover, as the rotation of the vehicle piston part 62 is prevented orreduced, the durability of an airtight seal which is provided on thevehicle piston part 62 or faces the vehicle piston part 62 may beimproved. In addition, since the unnecessary behavior of the vehiclebody 6 is prevented or reduced, the safety of a vehicle may be improved.

The rear wheel elastic support part 80 may have a shape which surroundsthe outer surface of the vehicle cylinder part 66, and supports theupper end of a second elastic part 61. The rear wheel elastic supportpart 80 in accordance with the exemplary embodiment includes an elasticsupport body 82 which may have a shape surrounding the outer surface ofthe second cylinder body 68, and a plurality of protruding projections84 which project upward from the elastic support body 82. The protrudingprojections 84 are assembled to contact with the lower surface of thebody support member 69.

The upper end of the second elastic part 61 which uses a coil spring isseated against the elastic support body 82, and the lower end of thesecond elastic part 61 is connected to the vehicle body 6.

The piston guide 90 may have a shape which surrounds the outer surfaceof the rear wheel piston body 63, and is formed with a groove at aportion which faces the rotation suppressing guide part 75, in thevertical direction.

The rear wheel stopper 92 having a snap ring shape is provided on therear wheel piston body 63 which projects out of the lower end of thevehicle cylinder part 66. As the rear wheel stopper 92 is engaged withthe lower end of the first cylinder body 67 when the vehicle piston part62 is moved upward above a predetermined height, the rear wheel stopper92 prevents or reduces the release of the vehicle piston part 62.

FIG. 15 is a perspective view illustrating the input unit 100 inaccordance with the exemplary embodiment of the disclosure, FIG. 16 isan exploded perspective view of the input unit 100 in accordance withthe exemplary embodiment of the disclosure, FIG. 17 is a perspectiveview illustrating a lead nut part 104 assembled in an input housing part110 in accordance with the exemplary embodiment of the disclosure, FIG.18 is a perspective view illustrating a state in which an input pistonpart 113 is disassembled from the input housing part 110 in accordancewith the exemplary embodiment of the disclosure, FIG. 19 is across-sectional view illustrating a process of lowering the input pistonpart 113 in accordance with the exemplary embodiment of the disclosure,and FIG. 20 is a cross-sectional view illustrating a process of raisingthe input piston part 113 in accordance with the exemplary embodiment ofthe disclosure.

As illustrated in FIGS. 15, 16, 17, 18, 19, and 20, the input unit 100may have various shapes without departing from a technical idea that theinput unit 100 adjusts the height of the vehicle body 6 by supplying theworking fluid 4 to the front wheel output unit 20 and the rear wheeloutput unit 60 or recovering the supplied working fluid 4. The inputunit 100 in accordance with the exemplary embodiment includes thedriving part 101, a reduction part 102, a bearing part 103, a lead nutpart 104, a lead screw 107, a hydraulic seal member 109, an inputhousing part 110, the input piston part 113, and a connection part 115.

The driving part 101 is supplied with electric energy and generatesrotational power. The driving part 101 in accordance with the exemplaryembodiment employs an electric motor, and the reduction part 102 isprovided in succession to the driving part 101. The output shaft of thedriving part 101 is connected to the reduction part 102, and the outputshaft of the reduction part 102 is connected to the lead nut part 104.

The reduction part 102 increases a torque by receiving the power of thedriving part 101, and rotates the lead nut part 104. The reduction part102 is decelerated by using a planetary gear, and the lead nut part 104is provided in succession to the reduction part 102.

The lead nut part 104 may have various shapes without departing from atechnical idea that the lead nut part 104 is threadedly coupled to theouter surface of the lead screw 107 and is rotatably coupled in theinput housing part 110. The lead nut part 104 in accordance with theexemplary embodiment includes a lead nut body 105 which has the shape ofa pipe extending in the vertical direction, and a lead nut wing 106which projects in the horizontal direction at the middle portion of thelead nut body 105 and supports the lower end of the bearing part 103.

A thread is formed on the inner surface of the lead nut body 105, andthe upper end of the lead nut body 105 is spline-coupled to thereduction part 102 and receives rotational power therefrom.

The lead screw 107 may have various shapes without departing from atechnical idea that the lead screw 107 is inserted into the input pistonpart 113 and is linearly moved in the vertical direction by receivingexternal power. The lead screw 107 in accordance with the exemplaryembodiment has the shape of a screw bar which is formed with a thread onthe outer surface thereof. A screw wing 108 extends in the horizontaldirection adjacent to the lower end of the lead screw 107.

The lead screw 107 is threadedly coupled to the inner surface of thelead nut body 105, and thus, the rotation of the input piston part 113which is coupled to the lead screw 107 is prevented or reduced.Therefore, by the rotation of the lead nut part 104, the lead screw 107and the input piston part 113 are moved in the vertical direction.

The input housing part 110 may have a shape which has a space where theworking fluid 4 is stored and which is open at the upper end thereof.The input housing part 110 in accordance with the exemplary embodimentincludes an input housing body 111 which has the shape of a pipeextending in the vertical direction, and an input housing cover 112which closes the lower end of the input housing body 111.

The input piston part 113 may have various shapes without departing froma technical idea that the input piston part 113 is positioned in theinput housing part 110 and is moved along the lengthwise direction ofthe input housing part 110. The input piston part 113 in accordance withthe exemplary embodiment forms an opening which is open upward, and isfastened to the lead screw 107.

Since a plurality of projections which project outward from the sidesurface of the input piston part 113 are inserted into groove partswhich are formed on the inner surface of the input housing part 110, therotation of the input piston part 113 and the lead screw 107 isprevented or reduced.

The connection part 115 may have various shapes without departing from atechnical idea that the connection part 115 connects the input pistonpart 113 and the lead screw 107. The connection part 115 uses at leastone of a first locking member 116, a second locking member 117 and athird locking member 118.

FIG. 25 is a perspective view illustrating a state in which the leadscrew 107 and the input piston part are connected by the third lockingmember 118 in accordance with the exemplary embodiment of thedisclosure, FIG. 26 is a cross-sectional view illustrating the inputpiston part 113 and the lead screw 107 separated from each other with ahydraulic seal member 109 interposed therebetween in accordance with theexemplary embodiment of the disclosure, FIG. 27 is a cross-sectionalview illustrating the input piston part 113 and the lead screw 107coupled with each other with the hydraulic seal member 109 interposedtherebetween, in accordance with the exemplary embodiment of thedisclosure, and FIG. 28 is a cross-sectional view illustrating a statein which the lead screw 107 and the input piston part 113 are connectedwith each other by the third locking member 118 in accordance with theexemplary embodiment of the disclosure.

As illustrated in FIGS. 25, 26, 27, and 28, the connection part 115 inaccordance with the exemplary embodiment includes the third lockingmember 118 which passes through and connects the input piston part 113and the lead screw 107 in the vertical direction.

After the hydraulic seal member 109 is positioned between the screw wing108 and the input piston part 113, the lead screw 107 and the inputpiston part 113 are connected with each other by using the third lockingmember 118, with the screw wing 108 brought into contact with the bottomsurface of the input piston part 113.

The third locking member 118 is locked to the lower end of the leadscrew 107 through a hole which is defined through the bottom of theinput piston part 113, in the vertical direction.

FIG. 29 is a perspective view illustrating a state in which the leadscrew 107 and the input piston part 113 are connected with each other bythe first locking member 116 in accordance with the exemplary embodimentof the disclosure, FIG. 30 is a cross-sectional view illustrating theinput piston part 113 and the lead screw 107 temporarily assembled, inaccordance with the exemplary embodiment of the disclosure, and FIG. 31is a cross-sectional view illustrating the lead screw 107 and the inputpiston part 113 connected with each other by the first locking member116 in accordance with the exemplary embodiment of the disclosure.

As illustrated in FIGS. 29, 30, and 31, the first locking member 116passes through and connects the input piston part 113 and the lead screw107 in the horizontal direction. The first locking member 116 inaccordance with the exemplary embodiment is locked in the horizontaldirection.

The screw wing 108 of the lead screw 107 is inserted into a groovedefined at the bottom of the input piston part 113, and, with the screwwing 108 brought into contact with the bottom surface of the inputpiston part 113, the first locking member 116 is locked in thehorizontal direction by passing through the input piston part 113 andthe screw wing 108. Therefore, the lead screw 107 is fastened to theinput piston part 113 even without using the separate hydraulic sealmember 109.

When assembling the input piston part 113 and the lead screw 107, in thecase where the hydraulic seal member 109 is provided between the inputpiston part 113 and the lead screw 107, the hydraulic seal member 109may break or be degraded in the sealing performance thereof due to thedeformation or fluctuation of the lead screw 107 and thus leakage mayoccur, and due to this fact, the operational performance of the inputunit 100 may be degraded.

However, since the lead screw 107 is fastened to the input piston part113 by the first locking member 116 without using the hydraulic sealmember 109, the number of parts and the manufacturing cost may bereduced and the durability performance of the input unit 100 may beimproved, due to the omission of the hydraulic seal member 109.

After, as illustrated in FIG. 30, aligning a hole which is definedthrough the lead screw 107 and a hole which is defined through the inputpiston part 113, the first locking member 116 is locked in thehorizontal direction as illustrated in FIG. 31. Therefore, even withoutusing the hydraulic seal member 109, because a hole having a highpossibility of leakage is not formed through the lower end of the inputpiston part 113, leakage suppression performance may be improved.

FIG. 32 is a perspective view illustrating the lead screw 107 and theinput piston part 113 connected with each other by the second lockingmember 117 in accordance with the exemplary embodiment of thedisclosure, FIG. 33 is a cross-sectional view illustrating the inputpiston part 113 and the lead screw 107 temporarily assembled, inaccordance with the exemplary embodiment of the disclosure, and FIG. 34is a cross-sectional view illustrating the lead screw 107 and the inputpiston part 113 connected with each other by the second locking member117 in accordance with the exemplary embodiment of the disclosure.

As illustrated in FIGS. 32, 33, and 34, the second locking member 117may have various shapes without departing from a technical idea that thesecond locking member 117 passes through the input piston part 113 andis locked to the lead screw 107. Accordance with the exemplaryembodiment, The second locking member 117 may be provided in a pluralnumber around the lead screw 107.

The second locking member 117 is also assembled in the horizontaldirection in the same manner as the first locking member 116, and atleast two locking members are provided in a plural number around theinput piston part 113. Since a way for fastening the second lockingmember 117 is similar to or the same as the way for fastening the firstlocking member 116, detailed description thereof will be omitted herein.

FIG. 21 is a cross-sectional view illustrating the replenishment unit130 connected to the input unit 100 in accordance with the exemplaryembodiment of the disclosure, FIG. 22 is a cross-sectional viewillustrating a process of transferring working fluid 4 stored in thereplenishment unit 130 to the input unit 100 in accordance with theexemplary embodiment of the disclosure, FIG. 23 is a perspective viewillustrating a valve part 133 in accordance with the exemplaryembodiment of the disclosure, and FIG. 24 is a cross-sectional viewillustrating a different type of valve part 133 in accordance with theexemplary embodiment of the disclosure.

As illustrated in FIGS. 21, 22, 23, and 24, the replenishment unit 130may have various shapes without departing from a technical idea that thereplenishment unit 130 is connected to the input unit 100 and suppliesthe working fluid 4 into the input unit 100 in the case where theworking fluid 4 stored in the input unit 100 is insufficient. Thereplenishment unit 130 in accordance with the exemplary embodimentincludes a supply pipe 131, a tank part 132, and a valve part 133.

By a hydraulic pressure generated as the input unit 100 linearly movesthe input piston part 113 upward and downward like a syringe, the outputunit 10 is operated and adjusts the height of the vehicle body 6. In thecase where leakage occurs by the operation of the input unit 100, thereplenishment unit 130 is configured to replenish a leaked amount of theworking fluid 4.

The supply pipe 131 is a pipe which connects the tank part 132 and theinput unit 100 and supplies the working fluid 4 stored in the tank part132, into the input unit 100. The supply pipe 131 in accordance with theexemplary embodiment is connected to the sidewall of the input housingpart 110 which forms an empty space due to leakage.

As illustrated in FIG. 22, in the case where the input piston part 113is raised to a maximum height, an empty space is formed by an amount bywhich the working fluid 4 leaks. Thus, in the case where the inputpiston part 113 is raised to the maximum height, the supply pipe 131 isconnected to the sidewall of the input housing part 110 under the inputpiston part 113.

The tank part 132 is connected to the supply pipe 131, and the workingfluid 4 for replenishment is stored in the tank part 132. The valve part133 is provided in the supply pipe 131, and permits unidirectional flowof the working fluid 4 from the tank part 132 to the input housing part110.

As illustrated in FIGS. 22 and 23, the valve part 133 includes a valveframe 135 which is fastened to the supply pipe 131, and a valve door 136which is rotatably coupled to the valve frame 135 and permits the flowof the working fluid 4 toward the input housing part 110 by beingrotated only when the internal pressure of the input housing part 110 isequal to or less than a predetermined pressure.

The valve frame 135 having a ring shape is fastened inside the supplypipe 131, and the valve door 136 is rotatably coupled to the valve frame135. The valve door 136 has a circular plate shape, and a spring memberis separately assembled at a position where the valve door 136 isconnected to the valve frame 135 and biases the valve door 136 in acounterclockwise direction (when viewed in FIG. 23). In a state in whichthe valve door 136 closes the passage of the valve frame 135, since thevalve door 136 is caught by a step portion which is formed in the valveframe 135, the additional rotation of the valve door 136 in thecounterclockwise direction is prevented or reduced.

Thus, in the case where a vacuum pressure is generated in the inputhousing part 110 due to the lack of the working fluid 4, since thevacuum pressure is larger than the force of the spring which biases thevalve door 136, the valve door 136 may be rotated and the working fluid4 in the tank part 132 may flow to the input housing part 110.

As illustrated in FIG. 24, a valve part 134 according to anotherexemplary embodiment includes a ball member 137 and a valve elasticmember 138. The ball member 137 has a spherical shape and is caughtinside the supply pipe 131. At a region where the ball member 137 isprovided, the supply pipe 131 has a flow path that gradually narrowsfrom the input unit 100 toward the tank part 132.

The valve elastic member 138 uses a member such as a spring, and biasesthe ball member 137 toward the tank part 132. Therefore, in the casewhere a vacuum pressure is generated due to the lack of the workingfluid 4, the working fluid 4 stored in the tank part 132 pushes away theball member 137 and flows into the input housing part 110.

As illustrated in FIGS. 21 and 22, when the input piston part 113 of theinput unit 100 is raised to a highest position, the supply pipe 131 isconnected to the input housing part 110 at a position immediately underthe input piston part 113. The supply pipe 131 is connected to the tankpart 132, and the valve part 133 as a check value is provided in thesupply pipe 131.

When the input piston part 113 is raised to the highest position, anegative pressure or a vacuum is generated by an amount by which theworking fluid 4 lacks. By the pressure generated at this time, the valvepart 133 is opened, and the working fluid 4 stored in the tank part 132flows into the input housing part 110 to replenish an insufficientamount of the working fluid 4, whereby the durability of the input unit100 and the output unit 10 may be improved.

As illustrated in FIG. 21, if the input piston part 113 is moveddownward, since the atmospheric pressure is formed at the position wherethe input housing part 110 is connected to the supply pipe 131, thevalve part 133 is not operated.

As illustrated in FIG. 22, if the input piston part 113 is moved to thehighest position, the vehicle body 6 is in the low mode, and, a negativepressure is generated by an amount of the working fluid 4 leaked, whichin turn, opens the valve part 133, and the working fluid 4 stored in thetank part 132 flows through the valve part 133 and is replenished intothe input housing part 110.

As illustrated in FIGS. 3 and 52, the hydraulic pressure measurementunit 140 is connected to the input unit 100, measures a hydraulicpressure of the working fluid 4, and transfers a measurement value tothe control unit 150. The vehicle height sensor 180 measures a height ofthe vehicle body 6. The vehicle height sensor 180 may measure a heightof the vehicle body 6 by radiation of light rays, and various methodssuch as a method of measuring a height change of the vehicle body 6 bymeasuring the rotation of a mechanism according to the height change ofthe vehicle body 6 may be used.

The displacement sensor 160 measures a process displacement of theoutput unit 10. The displacement sensor 160 in accordance with theexemplary embodiment measures a length change of the front wheel outputunit 20 and a length change of the rear wheel output unit 60.

The rotation measurement sensor 170 measures an rpm of the driving part101 which is provided in the input unit 100. As the rotation measurementsensor 170, an encoder or the like may be used.

The control unit 150 receives measurement values of the hydraulicpressure measurement unit 140, the displacement sensor 160, the rotationmeasurement sensor 170 and the vehicle height sensor 180, and calculatesa displacement of the output unit 10 and a load change in the vehiclebody 6.

In the high mode in which the length of the output unit 10 is longest,the height of the vehicle body 6 is kept highest, and the measurementvalue of the hydraulic pressure measurement unit 140 is largest.

In the low mode in which the length of the output unit 10 is shortest,the height of the vehicle body 6 is kept lowest, and the measurementvalue of the hydraulic pressure measurement unit 140 is smallest.

FIG. 41 is a view illustrating the stiffness adjustment unit 200connected to a connection pipe 5, in accordance with the exemplaryembodiment of the disclosure, FIG. 42 is a cross-sectional viewillustrating a first stopper 205 being brought into contact with a fixedstopper 207 in accordance with the exemplary embodiment of thedisclosure, FIG. 43 is a cross-sectional view illustrating the fixedstopper 207 positioned between the first stopper 205 and a secondstopper 206, in accordance with the exemplary embodiment of thedisclosure, and FIG. 44 is a cross-sectional view illustrating thesecond stopper 206 being brought into contact with the fixed stopper 207in accordance with the exemplary embodiment of the disclosure.

As illustrated in FIGS. 41, 42, 43, and 44, the stiffness adjustmentunit 200 may have various shapes without departing from a technical ideathat the stiffness adjustment unit 200 is provided between the outputunit 10 and the input unit 100 and adjusts the stiffness of the workingfluid 4 to be supplied to the output unit 10. The stiffness adjustmentunit 200 in accordance with the exemplary embodiment is provided betweenthe front wheel output unit 20 and the input unit 100, and includes astiffness adjustment body 201, a floating piston 202, an adjustmentspring 203, a sealing member 204, a first stopper 205, a second stopper206, and a fixed stopper 207.

The output unit 10 to which the stiffness adjustment unit 200 isconnected is the front wheel output unit 20 which adjusts the height ofthe front wheel-side vehicle body 6, and includes the first elastic part21 which elastically supports the vehicle body 6.

The stiffness adjustment body 201 is connected to the output unit 10 andthe input unit 100 through a pipe, and the working fluid 4 is stored inthe stiffness adjustment body 201. The working fluid 4 is stored in thelower part of the stiffness adjustment body 201, and the floating piston202 and the adjustment spring 203 are sequentially assembled in theupper part of the stiffness adjustment body 201.

The floating piston 202 is positioned in the stiffness adjustment body201, and is moved in the vertical direction by being pushed by theworking fluid 4. The sealing member 204 may have a shape which surroundsthe outer surface of the floating piston 202, and prevents or reducesthe working fluid 4 from flowing between the outer surface of thefloating piston 202 and the inner surface of the stiffness adjustmentbody 201.

The adjustment spring 203 is positioned on the floating piston 202, andbiases the floating piston 202 downward.

The first stopper 205 projects outward from the side surface of thefloating piston 202. The second stopper 206 is positioned above thefirst stopper 205 to face the first stopper 205, and projects outwardfrom the side surface of the floating piston 202. The fixed stopper 207positioned between the first stopper 205 and the second stopper 206, andprojects inward from the inner surface of the stiffness adjustment body201.

As illustrated in FIG. 43, in a mid mode in which the fixed stopper 207is separated from the first stopper 205 and the second stopper 206, theadjustment spring 203 and the first elastic part 21 reduce a pressurechange of the working fluid 4.

As the stiffness adjustment unit 200 is used, stiffness may be changeddepending on a height of the vehicle body 6. Since a case where thevehicle body 6 is in the high mode corresponds to a case where a vehicletravels off road, the stiffness of the working fluid 4 needs to be high.Also, since a case where the vehicle body 6 is in the low modecorresponds to a case where a vehicle travels at a high speed, thestiffness of the working fluid 4 needs to be high.

Since a case where the vehicle body 6 is in the mid mode corresponds toa usual running mode, the stiffness of the working fluid 4 needs to belower than the case of the low mode. Therefore, by changing stiffness ina vehicle depending on a height of the vehicle body 6, ride quality anddriving stability may be increased.

The stiffness adjustment unit 200 is an accumulator for stiffnessadjustment, and a spring stiffness of the adjustment spring 203 which isprovided in the stiffness adjustment unit 200 is set to k₂. A springstiffness of the first elastic part 21 which is provided in the outputunit 10 is set to k₁, and the stiffness of the vehicle body 6 isoptimally set in the case where the vehicle body 6 is in the mid mode.

On the assumption that the adjustment spring 203 and the first elasticpart 21 are connected in series, K_(vehicle) as optimal stiffness in thecase where the vehicle body 6 is in the mid mode is calculated asfollows.1/K _(vehicle)=1/k ₁+1/k ₂.

In the case where the height of the vehicle body 6 is in the mid mode, aload change in the output unit 10 causes a pressure change in the outputunit 10, and the stiffness adjustment unit 200 receives the pressurechange and absorbs vibration with the stiffness of k₂.

As illustrated in FIGS. 3 and 44, in the low mode in which the length ofthe output unit 10 decreases and the height of the vehicle body 6decreases, the second stopper 206 is caught by the fixed stopper 207. Inthe low mode, the input unit 100 is operated, and the working fluid 4flows from the output unit 10 to the input unit 100. At this time, asthe working fluid 4 in the stiffness adjustment unit 200 also flows tothe input unit 100, the floating piston 202 is moved downward.

In the low mode, the pressure of the working fluid 4 is lowest, and dueto this fact, a hydraulic pressure change of the working fluid 4 cannotbe transferred to the stiffness adjustment unit 200.

Thus, K_(vehicle)=k₁ results.

As the stiffness adjustment unit 200 is provided between the output unit10 and the input unit 100, stiffness may be increased in the high modeand the low mode and may be decreased in the mid mode, whereby thedriving stability and ride quality of a vehicle may be improved.

As illustrated in FIGS. 4 and 42, in the high mode in which the lengthof the output unit 10 increases and the height of the vehicle body 6increases, the first stopper 205 is caught by the fixed stopper 207. Inthe high mode, the input unit 100 is operated, and the working fluid 4flows to the output unit 10. At this time, the working fluid 4 is alsosupplied to the stiffness adjustment unit 200, and the floating piston202 is moved upward.

The output unit 10 operates in the high mode, the mid mode and the lowmode depending on a height of the vehicle body 6, and the hydraulicpressure of the working fluid 4 is highest in the high mode and islowest in the low mode.

In the high mode, since a hydraulic pressure is high, the movement ofthe floating piston 202 in the stiffness adjustment body 201 isprevented or reduced by the fixed stopper 207, and thus, the influenceof k₂ as the spring stiffness of the adjustment spring 203 disappears.Thus, K_(vehicle)=k₁ results.

FIG. 45 is a diagram schematically illustrating the front wheel outputunit 20 in accordance with the exemplary embodiment of the disclosure,FIG. 46 is a diagram schematically illustrating the vehicle heightadjustment system operating in the high mode and the low mode, inaccordance with the exemplary embodiment of the disclosure, FIG. 47 is adiagram schematically illustrating the front wheel output unit 20connected to the vehicle body 6 with a load of the vehicle body 6applied to the front wheel output unit 20, in accordance with theexemplary embodiment of the disclosure, FIG. 48 is a diagramillustrating a first load transferred to the front wheel output unit 20when the vehicle height adjustment system is operated in the high modein accordance with the exemplary embodiment of the disclosure, and FIG.49 is a diagram illustrating a second load transferred to the frontwheel output unit 20 when the vehicle height adjustment system isoperated in the low mode in accordance with the exemplary embodiment ofthe disclosure.

As illustrated in FIGS. 45, 46, 47, 48, and 49 and 52, a length changeof the front wheel output unit 20 may be calculated by using thehydraulic pressure measurement unit 140.

As illustrated in FIG. 45, the front wheel output unit 20 is provided onthe wheel support 8 which supports the wheel 7. Since the front wheeloutput unit 20 supports the vehicle body 6, a height of the vehicle body6 changes depending on a length change of the front wheel output unit20.

As illustrated in FIG. 46, in the high mode in which the length of thefront wheel output unit 20 is increased to the maximum, an angle formedby the front wheel output unit 20 and a virtual vertical line becomesA1. In the low mode in which the length of the front wheel output unit20 is reduced to the minimum, an angle formed by the front wheel outputunit 20 and a virtual vertical line becomes A2.

As illustrated in FIG. 47, in a state in which a force by a load W ofthe vehicle body 6 act in the direction of a vertical line and the frontwheel output unit 20 is connected to the vehicle body 6, the magnitudeof a force to be transferred to the front wheel output unit 20 ischanged depending on a change in an angle formed by the front wheeloutput unit 20 and the vertical line.

As illustrated in FIG. 48, a force applied to the front wheel outputunit 20 in the high mode is F1, and an angle formed by F1 and thevertical load W is A1.

As illustrated in FIG. 49, a force applied to the front wheel outputunit 20 in the low mode is F2, and an angle formed by F2 and thevertical load W is A2. A1 is smaller than A2, and F1 is larger than F2.

In this way, a height of the vehicle body 6 is changed depending on alength change of the front wheel output unit 20. Accordingly, a force tobe transferred to the front wheel output unit 20 is changed, and apressure of the working fluid 4 which operates the front wheel outputunit 20 is also changed.

Therefore, the control unit 150 may calculate a change in the length ofthe front wheel output unit 20, through a change in a hydraulic pressuremeasured by the hydraulic pressure measurement unit 140. A hydraulicpressure value of the working fluid 4 is smallest in the low mode, andis largest in the high mode.

Meanwhile, as illustrated in FIGS. 35 and 36, in the rear wheel outputunit 60, the vehicle piston part 62 and the vehicle cylinder part 66 arepositioned on the second elastic part 61, and the length of the rearwheel output unit 60 is changed as the vehicle piston part 62 is movedby the supply of the working fluid 4.

The load axis of the second elastic part 61 as a spring is changed bythe movement of the vehicle piston part 62, and due to this fact, awheel rate is changed. Due to a change in wheel rate, a vehicle heightadjustment amount and a load by the operation of the rear wheel outputunit 60 are changed.

As the length of the rear wheel output unit 60 is changed, a hydraulicpressure value of the working fluid 4 is changed. By measuring such ahydraulic pressure value, a displacement of the rear wheel output unit60 may be estimated.

In the device 1 for adjusting a height of a vehicle in accordance withthe exemplary embodiment, a displacement of the output unit 10 may beestimated through the hydraulic pressure measurement unit 140 mountedinstead of a sensor for sensing a displacement of the output unit 10. Inthis case, by removing the displacement sensor 160 of the output unit10, the number of parts and the manufacturing cost may be reduced.

FIG. 50 is a diagram illustrating a first table stored in the controlunit 150 in accordance with the exemplary embodiment of the disclosure,and FIG. 51 is a diagram illustrating a second table stored in thecontrol unit 150 in accordance with the exemplary embodiment of thedisclosure.

As illustrated in FIGS. 50 and 52, in the control unit 150, there isstored a first table M1 in which, when X data indicates an increase inthe load of the vehicle body 6 and Y data indicates an increase in thedisplacement of the output unit 10, the same value from the vehicleheight sensor 180 represents a first line 51 that slopes right downward.

In the first table M1 in accordance with the exemplary embodiments, Xdata as horizontal data indicates an increase in the load of the vehiclebody 6, and increases in the unit of 50 kg from left to right. In thefirst table M1, Y data as vertical data indicates an increase in thedisplacement of the output unit 10. The displacement of the output unit10 is set to 0 in the mid mode, is set to a positive number in the highmode, and is set to a negative number in the low mode, and thedisplacement of the output unit 10 gradually increases from the toptoward the bottom.

In the first table M1, a value of the vehicle height sensor 180 islargest at the left bottom end, and is smallest at the right top end.The first table M1 has Y data arranged vertically, and, in the Y data,the displacement of the output unit 10 increases toward the bottom anddecreases toward the top.

When a measurement value from the vehicle height sensor 180 whichmeasures a height of the vehicle body 6 is expressed as x in the firsttable M1, the first line S1 that slopes right downward is obtained.

In the control unit 150, through the first table M1, a plurality ofinput values from the vehicle height sensor 180 are inputted, and aplurality of first lines S1 corresponding to the input values from thevehicle height sensor 180 are stored.

As illustrated in FIGS. 51 and 52, in the control unit 150, there isstored a second table M2 in which, when X data indicates an increase inthe load of the vehicle body 6 and Y data indicates an increase in thedisplacement of the output unit 10, the same value from the hydraulicpressure measurement unit 140 represents a second line S2 that slopesleft downward.

In the second table M2, a value of the hydraulic pressure measurementunit 140 is largest at the right bottom end, and is smallest at the lefttop end.

In the second table M2 in accordance with the exemplary embodiment, Xdata as horizontal data indicates an increase in the load of the vehiclebody 6, and increases in the unit of 50 kg from left to right. In thesecond table M2, Y data as vertical data indicates an increase in thedisplacement of the output unit 10, and the displacement of the outputunit 10 gradually increases from the top toward the bottom.

In the control unit 150, through the second table M2, a plurality ofinput values from the hydraulic pressure measurement unit 140 areinputted, and a plurality of second lines S2 corresponding to the inputvalues from the hydraulic pressure measurement unit 140 are stored.

When a measurement value from the hydraulic pressure measurement unit140 is expressed as y in the second table M2, the second line S2 thatslopes left downward is obtained.

In the device 1 for adjusting a height of a vehicle in accordance withthe exemplary embodiment, the control unit 150 may calculate adisplacement of the output unit 10 and a load of the vehicle body 6, byusing measurement values from the vehicle height sensor 180 and thehydraulic pressure measurement unit 140.

The control unit 150 selects a corresponding first line S1 in the firsttable M1 based on a measurement value from the vehicle height sensor180, and selects a corresponding second line S2 in the second table M2based on a measurement value from the hydraulic pressure measurementunit 140.

The control unit 150 may calculate a displacement of the output unit 10and a load change of the vehicle body 6, by calculating an intersectionof the first line S1 and the second line S2 which are selected.

To this end, the control unit 150 stores tables indicating displacementsof the output unit 10 and load increases of the vehicle body 6. In thefirst table M1, a first line S1 which is defined by connecting the samemeasurement value from the vehicle height sensor 180 is set for eachmeasurement value from the vehicle height sensor 180.

In the second table M2, a second line S2 which is defined by connectingthe same measurement value from the hydraulic pressure measurement unit140 is set for each measurement value from the hydraulic pressuremeasurement unit 140.

The first line S1 is drawn in a right downward direction, and the secondline S2 is drawn in a left upward direction.

For example, when a displacement of the output unit 10 is MID and a loadchange is 0 kg in the first table M1, by assuming that a value from thevehicle height sensor 180 is x, if a displacement of the output unit 10is 5 mm and a load value is 100 kg, a vehicle height decreases and avalue from the vehicle height sensor 180 is obtained as x.

Further, when a displacement of the output unit 10 is MID and a loadchange is 0 kg in the second table M2, by assuming that a measurementvalue from the hydraulic pressure measurement unit 140 is y, if adisplacement of the output unit 10 is −5 mm and a load of the vehiclebody 6 is 100 kg, a measurement value from the hydraulic pressuremeasurement unit 140 is obtained as y.

The control unit 150 selects a first line S1 which has the same orsimilar value, in the stored first table M1, based on a measurementvalue from the vehicle height sensor 180. The control unit 150 selects asecond line S2 which has the same or similar value, in the stored secondtable M2, based on a measurement value from the hydraulic pressuremeasurement unit 140.

By calculating a point where the first line S1 and the second line S2intersect with each other, a load of the vehicle body 6 and adisplacement of the output unit 10 are estimated.

Since a displacement of the output unit 10 and a load change of thevehicle body 6 may be measured by using the hydraulic pressuremeasurement unit 140 and the vehicle height sensor 180 instead of thedisplacement sensor 160 and a load sensor of the device 1 for adjustinga height of a vehicle, the manufacturing cost may be reduced due to areduction in the number of parts, and, since a weight change of thevehicle body 6 may be estimated, assistance may be provided to thedynamic behavior of a vehicle.

As is apparent from the above descriptions, according to the exemplaryembodiment of the disclosure, the number of parts of a vehicle heightadjustment system may be reduced as compared to the conventional art,and thereby, the manufacturing cost may be reduced. Also, since adisplacement of the output unit 10 and a load change of the vehicle body6 may be measured based on measurement values from the vehicle heightsensor 180 and the hydraulic pressure measurement unit 140, themanufacturing cost may be reduced.

Further, since the rotation of the damper rod part 22, the piston part27 and the vehicle piston part 62 is prevented or reduced, thedurability of parts which are brought into contact with the damper rodpart 22, the piston part 27 and the vehicle piston part 62 may beimproved. Moreover, since the rotation of the damper rod part 22, thepiston part 27 and the vehicle piston part 62 is prevented or reducedand thus unnecessary behavior is prevented or reduced, the drivingsafety of a vehicle may be improved.

In addition, by providing the stiffness adjustment unit 200, vehiclestiffness may be changed in conformity with a height of the vehicle body6, and thus, ride quality and driving stability may be increased.Besides, since stiffness is increased in the case where the vehicle body6 is in the high mode and the low mode and is decreased in the casewhere the vehicle body 6 is in the mid mode, ride quality and drivingstability may be increased.

Furthermore, since the input piston part 113 and the lead screw 107 arefastened as the first locking member 116 or the second locking member117 is locked in the horizontal direction in a state in which the inputpiston part 113 and the lead screw 107 are brought into contact witheach other, a sealing member 204 may be omitted, the number of parts maybe reduced, and the manufacturing cost may be reduced.

Also, in the case where the working fluid 4 stored in the input unit 100leaks, since the working fluid 4 stored in the tank part 132 flows intothe input unit 100 and thus automatically replenishes the working fluid4, the durability of the device 1 for adjusting a height of a vehiclemay be improved.

Further, according to the exemplary embodiment of the disclosure, sincethe control unit 150 which receives a measurement value from thehydraulic pressure measurement unit 140 calculates a displacement of theoutput unit 10, a separate sensor for measuring a displacement of theoutput unit 10 may be omitted, and thereby, the manufacturing cost maybe reduced.

According to the exemplary embodiments of the disclosure, the vehicleheight adjustment system may have reduced number of parts compared tothe conventional art, and thereby, the manufacturing cost may bereduced.

Also, according to the exemplary embodiments of the disclosure, arotational movement of a piston part may be suppressed, the durabilityof parts brought into contact with the piston part may be improved.

Further, according to the exemplary embodiments of the disclosure,unnecessary behaviors of the piston part such as the rotational movementmay be suppressed, and therefore, the driving safety of the vehicle maybe improved.

Although exemplary embodiments of the present disclosure have been shownand described hereinabove, the present disclosure is not limited tospecific exemplary embodiments described above, but may be variousmodified by those skilled in the art to which the present disclosurepertains without departing from the scope of the disclosure as disclosedin the accompanying claims. In addition, such modifications should alsobe understood to fall within the scope of the present disclosure.

What is claimed is:
 1. A vehicle height adjustment system, comprising: acylinder housing part having an inner space configured to receiveworking fluid; a piston part positioned in the cylinder housing part,the piston part configured to move linearly, in response to a workingfluid, in a moving direction along the cylinder housing part; and arotation suppressing bracket coupled to the cylinder housing part andconnected to a side surface of the piston part, the rotation suppressingbracket configured to suppress rotational movement with respect to themoving direction of the piston part, wherein the piston part comprises:a piston body positioned in the cylinder housing part and configured tomove linearly in the moving direction; and a side engagement groove partformed on a side surface of the piston body having a groove shapeextending along the moving direction of the piston body, wherein therotation suppressing bracket comprises: a bracket body having a shape ofa ring which is brought into contact with an end of the cylinder housingpart; and a first engagement protrusion extending from the bracket bodyand inserted into the side engagement groove part, wherein the cylinderhousing part comprises a fastening groove part formed on the end of thecylinder housing part, and wherein the rotation suppressing bracketfurther comprises: a second engagement protrusion extending from thebracket body, and inserted into and engaged in the fastening groovepart.
 2. The vehicle height adjustment system according to claim 1,wherein the first engagement protrusion comprises a plurality of firstengagement protrusion parts extending from the bracket body.
 3. Thevehicle height adjustment system according to claim 1, wherein thesecond engagement protrusion comprises a plurality of second engagementprotrusion parts extending from the bracket body.
 4. The vehicle heightadjustment system according to claim 1, further comprising: an outputcover fastened to the cylinder housing part while surrounding therotation suppressing bracket.
 5. The vehicle height adjustment systemaccording to claim 1, further comprising a damper rod, the damper rodcomprising a protrusion part protruding from the damper rod, wherein thepiston part further comprising a guide part formed to have a grooveshape facing the protrusion part, and wherein the protrusion part isinserted into the guide part.
 6. The vehicle height adjustment systemaccording to claim 5, wherein the protrusion part inserted into theguide part is configured to suppress rotational movement of the damperrod with respect to the moving direction.
 7. A vehicle height adjustmentsystem, comprising: an output unit connected to a vehicle body forreducing vibration, the output unit configured to change its length inresponse to transfer of working fluid to adjust a height of the vehiclebody with respect to ground; a connection pipe connected to the outputunit; and an input unit connected to the connection pipe, the input unitconfigured to supply the working fluid to the output unit through theconnection pipe, wherein the output unit comprises: a cylinder housingpart having an inner space configured to receive the working fluid; apiston part positioned in the cylinder housing part, the piston partconfigured to move linearly in a moving direction in response to theworking fluid transferred to the cylinder housing part; and a rotationsuppressing bracket coupled to the cylinder housing part, the rotationsuppressing bracket comprising a first engagement protrusion formed onthe side surface of the rotation suppressing bracket, wherein the pistonpart comprises: a piston body positioned in the cylinder housing partand configured to move linearly in the moving direction; and a sideengagement groove part formed on a side surface of the piston bodyhaving a groove shape and extending along the moving direction of thepiston body, the first engagement protrusion of the rotation suppressingbracket being inserted into the side engagement groove part, wherein therotation suppressing bracket comprises a bracket body having a shape ofa ring which is brought into contact with an end of the cylinder housingpart; and wherein the first engagement protrusion extends from thebracket body, wherein the cylinder housing part comprises a fasteninggroove part formed on the end of the cylinder housing part, and whereinthe rotation suppressing bracket further comprises a second engagementprotrusion extending from the bracket body, and inserted into andengaged in the fastening groove part.
 8. The vehicle height adjustmentsystem according to claim 7, wherein the output unit comprises at leastone of: a front wheel output unit configured to adjust a height of afront wheel-side vehicle body; and a rear wheel output unit configuredto adjust a height of a rear wheel-side vehicle body.
 9. The vehicleheight adjustment system according to claim 7, wherein the input unitcomprises: an input piston housing part containing the working fluid;and an input piston part configured to move in a vertical direction totransfer the working fluid between the input unit and the output unit.10. The vehicle height adjustment system according to claim 9, whereinthe input unit further comprises: a driving part configured to generaterotational power for driving the input piston; and a reduction partconnected between the driving part and the input piston, the reductionpart configured to generate a torque by increasing the rotational powerof the driving part and transmit the torque to the input piston part.11. The vehicle height adjustment system according to claim 10, whereinthe input unit further comprises: a lead nut part configured to receivethe torque from the reduction part and rotate in response to thereceived torque; and a lead screw rotatably coupled to the lead nut partand connected to the input piston part, wherein the lead screw isconfigured to move in the vertical direction in response to the rotationof the lead nut part to move the input piston part in the verticaldirection.
 12. The vehicle height adjustment system according to claim7, further comprising a replenishment unit connected to the input unit,the replenishment unit configured to supply the working fluid into theinput unit.
 13. The vehicle height adjustment system according to claim12, further comprising a supply pipe connected between the input unitand the replenishment unit, wherein the replenishment unit is configuredto supply the working fluid into the input unit through the supply pipein response to a negative pressure formed in the input unit due to aleakage of the working fluid from operation.